This invention provides methods for improved sanitisation and the use of specific sanitising compositions.
Traditionally, hard-surface cleaners contain bleach as cleaning agent and as disinfectant. In particular, they contain high levels of chlorine bleach to achieve the required cleaning and disinfecting properties.
Research has shown that hydrogen peroxide bleach in laundry and dish washing detergents also has a disinfecting action, see for example M Blaser et al. in: The journal of infectious diseases, vol 149, no.1,1984.
More recently, detergent manufacturers have become interested in the disinfecting properties of these detergents. Various disclosures describe bleach systems which provide both cleaning and disinfecting during the laundering, for example DE 19616782, DE19605688, DE 19536082, WO9418297. Not all bleach systems which have disinfecting properties are suitable for detergents: they are not always compatible with other detergent ingredients, such as enzymes, or the levels of bleach required to obtain disinfecting are too high and may damage the fabrics.
The inventors now have found that most bleach systems known in the art, including TAED, percarbonate and perborate bleaches, effectively kill gram negative bacteria, but not effectively other micro-organisms, in particular, gram all positive bacteria. Also, it has been found that the anti-bacterial activity of for example TAED is dependent on the pH, resulting in a strong reduction of anti- bacterial activity on gram positive bacteria at a alkaline pH, such as for example during washing conditions.
Many soils, including body soil, mainly contain micro-organisms other than gram negative bacteria, in particular, gram positive bacteria. The inventors have found that detergents containing for example TAED and a peroxygen source do thus not effectively sanitise these types of soils, in particular at low temperatures as normally used by consumers during laundering, dish washing or other cleaning methods.
They have now found that specific hydrophobic bleaching agent effectively inactivate micro-organisms including gram positive bacteria, such as Enterococcus hirae and Staphyloccocus aureus bacteria. Thus, when these specific hydrophobic bleaching agents are used in detergents, not only excellent stain removal of bleachable stains and soils is achieved but also sanitisation.
It is believed that the specific hydrophobic bleaching agent have an improved surface activity for the peptidoglycan in the cell walls of, for example, yeast and gram positive bacteria compared to hydrophilic bleaching agents. It is believed that these specific hydrophobic agents thus penetrate and disrupt these cell walls more effectively than other hydrophilic bleaching agents.
Since the specific hydrophobic bleaching agent is found to be very effective, a further benefit can be that reduced levels of bleach can be employed.
Further improved sanitisation can be achieved when both hydrophilic and hydrophobic bleaching agents are employed, resulting in effective inactivation of both gram positive bacteria and gram negative bacteria.
The invention provides the use of a hydrophobic bleaching agent comprising a peroxyacid having a carbon chain of at least 9 carbon atoms for the reduction of the activity of micro-organism which have a cell wall which contain a high level of peptidoglycan.
When used herein, xe2x80x98high levels of peptidoglycanxe2x80x99 means that the micro-organisms have high levels of peptidoglycan, compared to gram negative bacteria. The cell walls preferably comprise a layer which predominantly comprises peptidoglycan They include yeast and in particular, gram positive bacteria.
When used herein, xe2x80x98reduction of the activity of the micro-organismsxe2x80x99 includes a reduction of the activity as defined in the CEN method prEN1276, 1993, (Comitxc3xa9 Europxc3xa9en de Normalisation) and CEN method prEN 1650. The reduction therein is preferably represented by a reduction of micro-organisms, preferably at least of 105, more preferably at least 106 or even more for actaria, or at least 104 or even at least 105 for yeast.
The reduction of the activity of the micro-organisms when used herein includes the reduction of any of the processes conducted by the micro-organisms which have a cell wall including high levels of peptidoglycan, compared to gram negative bacteria., including secretion of products but preferably the growth of the micro-organisms.
The invention also provides a method for reduction of the activity of micro-organisms, or preferably gram positive bacteria comprising the steps of contacting the micro-organism with an aqueous liquor comprising a hydrophobic bleaching agent comprising a peroxyacid having a carbon chain of at least 9 carbon atoms at a level of at least 100 ppm in the liquor, per 106 micro-organisms.